SUSY GUTs, DM and the LHC Smaragda Lola Dept. of Physics, University of Patras Collaborators [JCAP 1603 (2016) and in progress] R. de Austri, M.Canonni, J.Ellis, M. Gomez, Q. Shafi
Outline Ø No SUSY signal at the LHC (talks by G. Landsberg, J. Mamuzic) Severe constraints on at least the simplest realisations of susy Ø Still, we need to go beyond the SM, due to - Neutrino masses & mixing - Baryon asymmetry in the universe - Origin of dark matter - Large number of arbitrary parameters (mostly in mass sector) - Hierarchy problem, especially if further unification exists In this respect, SUSY GUTs have very attractive features Ø Non-minimal SUSY extensions - Break unification conditions of minimal schemes &/or - add new particles and interactions (softer fitting constraints)
o o o o Combine GUTs, SUSY and Flavour Symmetries Different predictions in various GUTs SO(10), Pati-Salam [NUHM] SU(5), Flipped SU(5) [non-universal sfermions] Can we distinguish different scenarios? What are the expected sparticle correlations in each scheme? Several constraints from DM considerations What can the LHC tell us on the underlying symmetries?
SUSY new particles and interactions Minimal SUSY Lagrangian very simple rule: all SM interactions + those where 2 particles are substituted by antiparticles i.e. Simplest SUSY models: - Missing Energy Signature - LSP as Dark Matter (one of our basic requirements)
Soft SUSY breaking terms
The simplest models may be too restrictive To search for/exclude SUSY unification need to first consider several alternative possibilities Vast number of models How to distinguish between them? Try to address at the same time the origin of mass, combining GUT and flavour symmetries
Fermion hierarchies from flavour symmetries (i.e. Why the top quark mass so much larger?) A family symmetry generates the observed hierarchies Charges such that only 3 generation masses allowed (0 flavour charges for 3 rd generation) The rest of the terms appear once the symmetry is broken Frogatt-Nielsen mechanism Similarly for other fermions, including neutrinos
SL, Ross
Pati-Salam Unification -Lepton number a 4 th color thus unifying quarks and leptons -L-R symmetry Fermions embedded as follows:
MINIMAL MODIFICATIOS TO SOFT TERM UNIVERSALITY: Fermion fields in the same 16 2 Higgs fields in different 10 representations
Fermions in different representations 2 Higgs fields in different 10 representations Ellis, Mustafaev, Olive, Velasco-Sevilla
SU(5) Flipped SU(5) - versus SU(5) Flipped SU(5) Different field assignment in representations different predictions (i.e. more freedom with stop masses as compared to SO(10), SU(5))
Could have gone even further (model dependent) Flavour symmetries determine soft SUSY terms L-R symmetric SU(5) L: (1,0,0) R: (3,2,0)
Dark Matter various possibilities
Parameter space scans with 2 sets: Set 1 is broader, up to 10 TeV Combined data accommodated easier with a heavy spectrum and Higgsino LSP Set 2 zooms to the lower mass spectrum where co-annihilations are expected Complex computations: SUSY Search: SuperBayeS, MultiNest RGE's: SoftSusy Relic Density: MicroOMEGAs Direct DM detection: DarkSUSY SusyBSG: B-Physics
Correlations between the non-universal soft scalar masses and DM in different SUSY GUTS (CMSSM fpr xu,d,5,r = 1 / too restrictive) SO(10) [and SU(5)]: stop mass tends to become very heavy Flipped SU(5)]: stop-coannihilations possible
Sparticle correlations
For completeness: Some comments on R-violating SUSY In addition to couplings generating fermion masses, Also VERY RICH FLAVOUR STRUCTURE 45 couplings violating lepton or baryon number X : Unacceptable proton decay - kill all couplings via R-parity (Fayet) ü OR, allow subsets by baryon / lepton parities (i.e. Ibanez, Ross) Colliders: Multi-lepton/jet events instead of missing energy Single sparticle productions possible LSP: unstable but, gravitino DM a viable possibility Its RPV-decays suppressed by: - Gravitino vertex (~1/Mp) - Phase space (light gravitino) - Loop factors (~ fermion mass) - Neutrino- neutralino mixing [Takayama, Yamaguchi], [Chemtob, Moreau] [Buchmuler, Covi, Hamaguchi, Ibarra, Yanagida] [SL, P. Osland, A. Raklev]
Predictions for R-violating operators in different GUTS: What type of processes favoured in different groups? (proceed similarly to discussion for fermion mass terms) L-R symmetric SO(10): similar LLE,LQD,UDD (only generation matters) - Bounds on products of couplings, due to correlations, translated to individual bounds /very restrictive [Ellis, SL, Ross] -1 coupling dominance disfavoured - Single sparticle productions disfavoured over MSSM ones, with RPV decays SU(5) with U(1) charges chosen to match lepton data Very different expected correlations Larger hierarchies and dominance of fewer couplings Single sparticle productions better accommodated Neutralinos-charginos couple to all 45 operators Ideal channels to study simultneously all hierarchies [Bomark, Choudhury, Kvellestad, SL, Osland, Raklev]
Conclusions o Can identify patterns of soft SUSY-breaking terms at the GUT scale, compatible with DM predictions and LHC spectra o The models predict different spectra for the same LSP mass, connecting possible observations with the underlying unified theory. o In particular, SO(10), SU(5), flipped SU(5) and Pati-Salam lead to very different predictions, and are distinguishable in future searches. o Flipped SU(5) and PS predict stop-lsp coannihilations that are absent in the other groups and can be explored in LHC searches.